What workup is indicated for scrotal and penile edema in a patient without heart failure who has been treated with multiple broad-spectrum antibiotics (BSA)?

Workup for Scrotal and Penile Edema in Non-Heart Failure Patient on Broad-Spectrum Antibiotics

Perform scrotal ultrasound with color Doppler as the primary diagnostic test to differentiate between infectious, vascular, and idiopathic causes of scrotal edema, while simultaneously evaluating for signs of necrotizing infection that would require urgent surgical intervention. 1

Initial Diagnostic Imaging

• Scrotal ultrasound with color Doppler is the first-line imaging modality to assess testicular perfusion, identify epididymo-orchitis, evaluate scrotal wall thickness and characteristics, and rule out testicular torsion or masses 1
• Look specifically for the "fountain sign" (increased peritesticular blood flow with reactive hydrocele) which suggests acute idiopathic scrotal edema, a self-limiting condition 2, 3
• Assess for scrotal wall thickening with heterogeneous striated and edematous appearance with increased vascularity, which characterizes acute idiopathic scrotal edema 1, 2
• Evaluate the epididymis for enlargement and increased flow on color Doppler, which indicates epididymo-orchitis (the most common cause of acute scrotal pain in adults) 1

Critical Red Flags Requiring Immediate Escalation

If any of the following are present, immediately obtain CT or MRI and surgical consultation:

• Crepitus, skin necrosis, or systemic sepsis suggest Fournier's gangrene, which requires immediate broad-spectrum IV antibiotics and urgent surgical debridement 1, 4
• Fever, severe pain, or signs of deeper infection beyond superficial edema mandate systemic antibiotics and surgical evaluation 4, 5
• Failure to improve within 72 hours of antibiotic therapy is a critical threshold that mandates surgical evaluation 5

Laboratory Evaluation

• Check complete blood count, inflammatory markers (ESR, CRP), renal function panel, and urinalysis with culture to identify infectious etiology and assess for systemic involvement 1, 2
• Monitor for sepsis with vital signs, lactate, and blood cultures if systemic symptoms are present, as 7.3% of severe genitourinary infections progress to urosepsis 5
• Consider testing for sexually transmitted infections (Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium) if epididymitis is suspected, particularly in sexually active patients 1, 6

Differential Diagnosis to Consider

Infectious Causes

• Epididymo-orchitis presents with enlarged epididymis, increased Doppler flow, scrotal wall thickening, and hydrocele; up to 20% have concomitant orchitis 1
• Fournier's gangrene is polymicrobial necrotizing fasciitis with painful scrotal/perineal swelling and sepsis; CT or MRI helps define extent 1, 4
• Chronic Chlamydia trachomatis infection can rarely cause elephantiasis-like changes 6

Non-Infectious Causes

• Acute idiopathic scrotal edema is painless, self-limiting, shows marked scrotal wall thickening with striated appearance and increased vascularity, but normal testes and epididymis 1, 2, 3
• Drug-induced edema from vasodilators, NSAIDs, or calcium channel blockers should be investigated 1
• Venous insufficiency or lymphatic obstruction 1
• Nephrotic syndrome if proteinuria is present 1

Management Algorithm Based on Findings

If Ultrasound Shows Epididymo-Orchitis:

• For patients >35 years or with risk factors for enteric organisms: Levofloxacin 500 mg orally once daily for 10 days or ofloxacin 300 mg orally twice daily for 10 days 1, 7
• For sexually active patients <35 years: Consider ceftriaxone 250 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 10 days 7
• Reevaluate after 3 days of therapy to assess response 7

If Ultrasound Shows Acute Idiopathic Scrotal Edema:

• Expectant management with NSAIDs for symptom relief; symptoms typically resolve within 72 hours 2, 3
• No antibiotics needed as this is a self-limiting condition 2, 3

If Clinical Concern for Fournier's Gangrene:

• Immediate broad-spectrum IV antibiotics covering gram-positive, gram-negative, and anaerobic organisms 1, 4
• Urgent surgical debridement with urinary diversion via suprapubic catheter; degree of internal necrosis vastly exceeds external signs 1

Common Pitfalls to Avoid

• Do not rely on topical antibiotics alone for scrotal infections; they are insufficient for deep or extensive infections requiring systemic therapy 4
• Do not delay systemic antibiotics in patients with fever, severe pain, or signs of deeper infection, as this leads to poor outcomes 4, 5
• Do not miss Fournier's gangrene in obese or immunocompromised patients (diabetes, malnutrition), as onset can be insidious with delayed presentation in up to 40% of cases 1
• Do not attribute all edema to infection without investigating other causes like drug-induced edema, venous insufficiency, or nephrotic syndrome 1